Triggering magnet and coil assembly for use with an ignition system including a permanent magnet alternator

ABSTRACT

A triggering magnet and coil assembly for use with a permanent magnet alternator and ignition system a a spark-ignited engine is disclosed. The ignition system includes a condenser discharge circuit using a silicon-controlled rectifier for controlling the charging and discharging of a condenser; the condenser when discharged being discharged through the primary winding of a step-up transformer having its secondary winding connected to the spark plug of the engine. Triggering signals for the siliconcontrolled rectifier are provided by the triggering magnet and coil assembly. The triggering magnet and coil assembly includes a core and two coils arranged and connected to minimize the effect of the leakage field established by the permanent magnets of the alternator.

United States Patent Michael J. Piteo Eniield, Conn.

Nov. 24, 1969 Nov. 30, i971 RIE. Phelon Company, Inc. East Longmeadow, Mm.

TRIGGERING MAGNET AND COIL ASSEMBLY FOR USE WIT I1 AN IGNITION SYSTEM INCLUDING A PERMANENT MAGNET ALTERNATOR 10 Claims, 7 Drawing Figs.

U.S. Cl 123/149 D, 123/148 E, 123/149 C Int. CL F021) 1/02 Field olSearch 123/148 E,

lnventor Appl. No. Filed Patented Assignee References Cited UNITED STATES PATENTS 7/1967 Hardin et a1.

3,452,730 7/1969 Stephens 123/148 E 3,464,397 9/1969 Burson 123/148 E 3,465,739 9/1969 Burson 123/148 E X 3,517,655 6/1970 .laulmes.. 123/148 E 3,527,266 9/1970 Santi 123/149 D 3,524,438 8/1970 .lanisch 123/148 E Primary Examiner Laurence M. Goodridge Assistant Examiner-Cort R. Flint Attorney-McCormick, Paulding & Huber ABSTRACT: A triggering magnet and coil assembly for use with a permanent magnet alternator and ignition system a a signals for the silicon-controlled rectifier are provided by the triggering magnet and coil assembly. The triggering magnet and coil assembly includes a core and two coils arranged and connected to minimize the effect of the leakage field established by the permanent magnets of the alternator.

PATENTEDunv 30 19m SHEET 3 [1F 3 FIGS FIG. 5.

TRIGGERING MAGNET AND COIL ASSEMBLY FOR USE WITH AN IGNITION SYSTEM INCLUDING A PERMANENT MAGNET ALTERNATOR BACKGROUND OF THE INVENTION This invention relates to ignition systems for spark-ignited engines, and deals more particularly with a triggering magnet and coil assembly for use with a breakerless ignition system including a permanent magnet alternator.

Several difi'erent types of breakerless ignition systems are known in the art. In these systems, the conventional breaker points are replaced by a transistor, a silicon-controlled rectifier, a thyratron, or another electronic switch means controlled in some manner by a triggering signal. These systems are generally more reliable than the equivalent mechanical breaker systems and normally have a longer service life because they are less subject to mechanical wear and deterioration. One such system is disclosed in copending US. Pat. No. 3,465,739.

In the system disclosed in the above-identified patent, a triggering magnet and coil assembly is positioned adjacent a rotating part of the motor. A series of pins, ribs, or other irregularities on the rotating part cooperate with the coil and magnet assembly to provide a flux circuit through the coils the reluctance of which changes in such a manner, as the pins, ribs or other irregularities move past the coil and magnet assembly, that a triggering signal is induced in the coil. The triggering signal of the coil is applied to the gate electrode of a silicon-controlled rectifier to turn on the silicon-controlled rectifier at the proper time in the engine cycle. When the siliconcontrolled rectifier is turned on, a high voltage is applied to a spark plug or other spark gap ignition device to produce a spark across the gap. Two or more of these irregularities are utilized to produce a spark advance. As shown in this patent, the rotating part of the engine adjacent which the triggering magnet and coil assembly is positioned may be the rim of the rotor of a permanent magnet alternator which includes a winding for supplying power to the ignition system.

The triggering magnet and coil assembly of this invention is a modification of the magnet and coil assembly disclosed in the above-identified patent. When the magnet and coil assembly of said patent is used adjacent the rim of the rotor of a permanent magnet alternator the rim of the rotor must be made of iron or other magnetic material so as to reduce the leakage flux field produced by the alternator magnets to a level at which it has no effect on the triggering coil. This is, if the leakage flux field is too great it may induce large enough voltages in the triggering coil as to cause triggering at improper times in the engine cycle particularly at higher engine speeds. The triggering magnet and coil assembly of this invention may be used with a permanent magnet alternator in which the rotor, except for the permanent magnet assemblies carried thereby, are made from aluminum or other nonmagnetic material the leakage field of the alternator magnets having little effect on the output voltage produced by the triggering coils.

The general object of this invention is, therefore, to provide an improved triggering magnet and coil assembly for use with a breakerless ignition system including a permanent magnet alternator.

SUMMARY OF THE INVENTION This invention resides in a triggering magnet and coil assembly for providing a triggering voltage to an electronic switching device, such as a silicon controlled rectifier, in a breakerless ignition system including a permanent magnet alternator having a rotor carrying permanent magnets. The triggering magnet and coil assembly are located close to the rotor and prominent irregularities on the rotor, its hub or some other part moving in unison therewith, sweep past the triggering magnet and coil assembly and induce a voltage in two separate coils of the assembly. Two or more of the irregularities or protrusions are used to provide a spark advance. The

induced voltage is applied to the electronic switch of the triggering system, thereby providing a voltage to the spark plug or other spark gap device utilized. The triggering magnet and coil assembly comprises a permanent trigger magnet, a laminated iron core attached to the trigger magnet and said two aforementioned coils which are wound on said core. The coils and core are arranged relative to the leakage field of the alternator magnets in such a manner that each has substantially the same instantaneous voltage induced therein by such leakage flux, and they are electrically connected to one another in series and in such a manner that the voltages induced in the two coils by the leakage flux are in series bucking relation to one another while the voltage induced therein by the field of the triggering magnet are in series aiding relation to one another. Accordingly, the voltages induced by the leakage flux cancel one another and have little effect on the output voltage appearing across the two coils.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary perspective view of a spark-ignited engine equipped with a permanent magnet alternator and an ignition system using a triggering magnet and coil assembly embodying this invention FIG. 2 is a vertical sectional view taken through the alternator rotor of FIG. 1 on a plane perpendicular to its axis, the windings of the alternator stator being shown schematically.

FIG. 3 is a fragmentary vertical sectional view taken through the rotor of FIG. I on a plane containing the rotor axis and showing the triggering magnet and coil assembly in elevation.

FIG. 4 is a schematic diagram of the ignition system of the engine of FIG. 1.

FIG. 5 is a schematic view showing the manner in which the two coils of the triggering magnet and coil assembly of FIG. I are electrically connected to one another and showing the direction of their windings relative to the path of the triggering magnet flux and the path of the leakage flux of the alternator magnets.

FIG. 6 is a vertical sectional view taken on a vertical plane containing the rotor axis showing an alternator utilizing a second embodiment of this invention with the triggering magnet and coil assembly thereof being shown in elevation.

FIG. 7 is a fragmentary sectional view taken on the line 7 7 of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning to FIGS. 1, 2 and 3, and first considering FIG. I, this figure shows fragmentarily a spark-ignited engine I including a permanent magnet alternator indicated generally at 17. The ignition system for the engine I includes a triggering magnet and coil assembly 2 mounted outside of and adjacent to the rim 3] of the alternatorrotor 18. This triggering magnet and coil assembly may be part of a larger assembly, indicated by the broken lines 4 of FIG. 1, including other parts of the ig-. nition system and suitable fixed to the adjacent stationary structure of the engine. For example, the assembly 4 may consist of a body of plastic in which the triggering magnet and coil assembly and other parts of the ignition system are potted, but except for the triggering magnet and coil assembly 2 the assembly 4 comprises no particular part of this invention and may vary widely as to construction and form.

The triggering magnet and coil assembly 2, as shown best in FIG. 3, comprises a cylindrical pennanent magnet 3 and a core comprised of laminated iron legs 5 and 7 attached to the ends of the magnet 3 as by a bolt or other fastener passing through the legs and the magnet. Two separate triggering coils are included in this assembly and consist of a first coil 9 wound on the leg 5 and a second coil 11 wound on the leg 7. The two coils 9 and 11 are identical, or substantially identical, to one another so as to have substantially equal voltages induced therein, and as explained in more detail hereinafter, are electrically connected in series with one another.

The illustrated alternator 17 is or may be a generally conventional permanent magnet alternator of the type used in spark ignition engines and includes a stator 25 fixed to a stationary structure of the engine, and the rotor 18 which is fixed to a shaft 29. The shaft 29 is rotated in synchronism with the operation of the engine and may be the crankshaft or camshaft of the engine. In any event, the shaft 29 is one which rotates at a speed directly related to that of the engine crankshaft so that a given angular displacement of the crankshaft results in an equivalent angular displacement of the alternator rotor. The rotor has a central hub 35 and its rim 31 is connected to this hub by a radial web. The stator 25 is located inside the rotor in the space between the hub 35 and the rim 31 and includes a core 24 of laminated magnetic material having twelve equally angularly spaced radially outwardly extending poles 21, 21. Eleven of the poles 21, 21 receive associated windings 23, 23 each having a relatively low number of turns of relatively heavy wire, and these windings are connected in series with one another to provide a source of alternating power for a load 41 as shown in FIG. 4. The load 41 may for example constitute a charging circuit for a battery used for starting the engine and/or a circuit including lights or other auxiliary electrically powered equipment. The twelfth pole 21 receives a winding 39 made up of a large number of turns, for example 4,000 turns, of relatively fine wire. This winding is used to provide a source of high-voltage power for the ignition system 40 shown in FIG. 4.

To provide a magnetic flux field for inducing voltages in the stator windings 23, 23 and 39, of the alternator, six magnet assemblies are imbedded in the rotor rim 31. Each of these magnet assemblies consists of two pole pieces 19, 19 and a tangentially charged permanent magnet 20. The two pole pieces 19, 19 provide a series of twelve alternatively magnetically charged pole faces on the inner surface of the rotor rim. It will therefore be obvious that as the rotor 18 is rotated alternating voltages will be induced in the various stator coils 23, 23 and 39. The voltage induced in the coil 29 is of course relatively high in comparison with that induced in each of the other coils 23, 23. During normal operation, the rotor 18 is rotated by the engine in the direction of the arrow 22.

Except for the magnet assemblies, the rotor 18 may be made from a nonmagnetic die cast material such as. aluminum or an aluminum alloy. When such nonmagnetic material is used for the rotor it does not confine the flux of the magnets 20, and a substantial leakage flux field, emanating from the magnets 20, 20, is formed around and in the vicinity of the rotor. The general nature of this leakage field in the zone surrounding the outer periphery of the rotor is shown generally by the flux lines 33, 33 of FIG. 2.

FIG. 4 shows the ignition system for the engine 1 of FIG. 1. This system uses the triggering magnet and coil assembly 2 and is otherwise generally similar to that shown and described in US. Pat. No. 3,465,739.As shown in FIG. 4, the ignition system is indicated generally at 40 and comprises the coil 39, a diode 45 connected across the coil, a diode 47, a capacitor 43, a silicon-controlled rectifier 49, the series-connected coils 9 and 11 of the triggering magnet and coil assembly, a step-up transformer 50 and a spark plug 55. The transformer 50 has a primary winding 51 and a secondary winding 53. The capacitor 43, through the action of the diode 45, is charged on the positive half cycles of the voltage induced in the coil 39. The diode 47 is used as a blocking diode to block discharge of the capacitor 43 back through the coil 39. When the silicon-controlled rectifier is turned off, the capacitor 43 will be charged and will remain charged until the silicon-controlled rectifier is switched to an on or conducting condition. When the siliconcontrolled rectifier 49 is turned on, the capacitor 43 is discharged through the primary winding 51 of the transformer 50, and this in turn induces a high voltage in the secondary winding 53 thereby creating a spark at the spark plug 55.

The triggering of the silicon-controlled rectifier 49 is controlled by the triggering coils 9 and 11 which are connected in series with one another between its gate electrode and cathode. As explained in more detail hereinafter in connection with FIG. 5, the two coils 9 and 11 are so connected to one another that the voltages induced therein by the flux field of the triggering magnet 3 are in series aiding relation to one another so as to add to one another and produce a voltage between their opposite ends, that is between the gate and cathode terminals of the silicon controlled rectifier, which is equal to approximately twice the voltage induced in each individual one of the coils.

The triggering magnet 3 and the magnetic core legs 5 and 7 provide a magnetic flux field passing through the coils 9 and 11 illustrated by the dotted lines 12, 12 of FIG. 3 and FIG. 5. The amount of this magnetic flux flowing through the coils 9 and 11 depends, among other things, on the reluctance of the magnetic circuit between the inner ends of the core legs 5 and 7, and irregularities are provided on the rotor rim 31 so that this reluctance is substantially different at different rotor positions. In the embodiment of the invention shown in FIGS. 1, 2 and 3 the irregularities on the rotor rim for varying the reluctance of the flux circuit between the ends of the trigger magnet core legs 5 and 7 consist of rectangular bars 13 and 15 of magnetic material fixed to the rotor rim 31. Both of these bars 13 and 15 extend axially of the rotor rim and are arranged to axially span the space between the core legs 5 and 7, and each protrudes radially outwardly from the surface of the rotor rim. The bars 13 and 15 have generally the same axial length and circumferential width, but the leading bar 13 is substantially radially shorter than the trailing bar 15. In the illustrated case the bars 13 and 15 are spaced circumferentially of the rotor rim about 20from each other.

The direction of rotation of the rotor 18 is indicated by the arrow 22 of FIG. 2. Therefore, during each revolution of the rotor the shorter leading bar 13 first passes beneath the triggering magnet core legs 5 and 7, and then 20later the taller trailing bar 15 passes beneath the core legs. When the shorter bar 13 passes beneath the core legs the reluctance of the flux circuit between their inner ends is reduced to some extent and a small voltage wave is induced in the coils 9 and 11. When the taller bar 15 later passes beneath the core legs, the reluctance of the flux circuit between their inner ends is further reduced and a larger voltage wave is induced in the coils 9 and 11.

The peak valve of the voltage waves induced in the coils 9 and 11 as the bars 13 and 15 pass beneath the triggering magnet and coil assembly 2 is dependent upon the rate of change of the reluctance of the trigger magnet flux circuit, and therefore on the speed of the rotor. The height of the bar 15 and other parameters are chosen such that even at low cranking speeds of the engine the voltages induced in the coils 9 and 11 at the moment the bar 15 passes beneath the assembly 2 are sufficient to turn on the silicon-controlled rectifier 49 thereby permitting a spark to be produced across the gap of the spark plug 55. The bar 15 in turn is so located on the rim 31 of the rotor that when it is positioned beneath the assembly 2 the crankshaft of the engine is at or near its top dead center position. At higher rotor and engine speeds a larger voltage wave is induced in the coils 9 and 11 by the shorter bar 13 as such bar passes beneath the assembly 2, and again the height of the bar 13 and other parameters of the system are chosen such that at or about a given engine speed the voltage induced in the coils 9 and 11 by the passes of the shorter bar 13 are sufficient to trigger the silicon controlled rectifier 49 to turn it on. Since the shorter bar 13 is approximately 20ahead of the taller bar 15, the firing of the spark plug at this high rotor speed accordingly occurs approximately 20in advance of the position at which firing occurs at low engine speeds. Of course, a 20advance has been shown herein by a way of example only and different degrees of advance may readily be obtained by varying the spacing between the two bars 13 and 15. Also, while the irregularities have been illustrated as being axially extending bars of magnetic material, it should be obvious that other forms and shapes of irregularities may be used to vary the reluctance of the triggering magnet flux circuit as such irregularities pass the triggering magnet and coil assembly. Also, a larger number of circumferentially spaced irregularities may be used, if desired, to provide different degree of advance at different speeds as described in more detail in the aforementioned US Pat. No. 3,465,739.

The construction of the triggering magnet and coil assembly 2 as above described has the additional important advantage of reducing the effect of the flux field of the alternator magnets 20, thereon so as to allow the rotor to be made predominantly of a nonmagnet material and/or to eliminate the need for a magnetic shield between the rotor and the triggering magnet and coil assembly. The manner in which this advantage is obtained may best be appreciated by consideration of FIG. 5 which schematically shows the physical arrangement and the direction of the winding of the two coils 9 and 11 relative to the flux field produced by the triggering magnets and the leakage flux field produced by the alternator magnets 20,20.

Referring to FIG. 5, the fiux field established by the triggering magnet is indicated by the broken line 12 and the leakage flux field established by the alternator magnets 20, 20 and as encountered at one position of the rotor by the coils 9 and 11 is indicated by the lines 33, 33. The arrows on these lines indicate the directions of the field at the moment depicted. It will be noted that as to the field 12 produced by the triggering magnet, the flux of this field moves downwardly relative to the coil 9 and upwardly relative to the coil 11 and these two coils are in turn so wound on their respective cores 5 and 7 and connected to one another, as in the manner shown, that as to the field 12 they are connected in series aiding relationship. On the other hand, as to the leakage field 33 it will be noted that the flux of this field moves downwardly relative to both of the coils 9 and 11, and therefore as to this field the'two coils 9 and 11 are connected to one another in series bucking relationship. More particularly, it should be noted that as to one triggering coil (the coil 9) the fluxes of the two fields move in the same direction and as to the other coil the fluxes ofthe two fields move in opposite directions, and so long as the coils are positioned that such a situation is obtained they may be wound and connected to achieve an addition of the voltages produced by the trigger magnet fiux and a cancellation of the voltages produced by the alternator magnet leakage flux.

Accordingly, the voltages induced in the coils 9 and 11 by the trigger magnetic field 12 add to one another and produce a voltage across the two opposite ends of the coils equal to approximately twice the voltage induced in each separate coil, but the voltages induced in the coils 9 and 11 by the leakage flux field tend to cancel one another and therefore produce no substantial output voltage across the two opposite ends of the coils. The possibility of the leakage flux field inducing large enough voltages in the triggering coils to cause triggering of the silicon-controlled rectifier at an improper time is therefore drastically reduced if not entirely eliminated. In order to obtain a cancellation of the voltages induced in the coils 9 and 11 by the leakage flux of the magnets 20, 20 the coils 9 and 11 should of course be positioned so that the leakage flux passing through both of the coils is in substantially the same direction and of substantially the same magnitude as indicated by FIG. 5. This may be obtained by arranging the coils, when used with a rotor such as shown, with their axes spaced and parallel to one another and located substantially in a plane passing through the rotor axis.

In FIGS. 1, 2 and 3 the triggering magnet and coil assembly 2 has been shown located outside of the alternator rotor adjacent its rim. This location is not, however, essential to the invention and other locations of the triggering magnet and coil assembly may be used if desired. For example referring to FIGS. 6 and 7, these figures show the triggering magnet and coil assembly located adjacent the hub of the alternator rotor. In the apparatus shown by these figures the alternator and triggering coil and magnet assembly are substantially identical to those of FIGS. 1, 2 and 3 and the various parts thereof have been given the same reference numerals as in such latter figures and need not be redescribed. An exception to this is,

however, the fact that the alternator rotor of FIG. 6 includes an axially elongated hub 350 which carries the axially extending radially protruding magnetic bars 13 and 15. The triggering magnet and coil assembly 2 is in turn located adjacent the hub 35a in the vicinity of the bars 13 and 15 so that these bars pass beneath the ends of the core legs 5 and 7 during each revolution of the rotor to induce voltages in the triggering coils 9 and 11 in the same manner as described above in connection with the device of FIGS. 1, 2 and 3. In this case the assembly 2 is located in that part of the leakage flux field of the alternator magnets that extends radially inwardly slightly to one side of the rotor rim 31, but the effect is the same as in FIG. 5. That is, the leakage flux tends to move in the same direction through both coils 9 and 11 and to thereby induce voltages in such coils which cancel one another due to the coils being connected in series bucking relation to such voltages.

Iclaim:

1. In a breakerless ignition system for a spark-ignited engine the combination comprising: a permanent magnet alternator having a rotor rotated in synchronism with the operation of said engine, said rotor including at least one permanent magnet establishing a leakage flux field in the vicinity of said rotor, a spark gap ignition device, means including an electronic switching device for causing the occurrence of a spark at the spark gap device as said switching device is switched from a first state to a second state, a triggering magnet, two triggering coils located near said rotor so as to be within said leakage field, means providing a circuit for the flux of said triggering magnet which circuit passes through both of said triggering coils and has a reluctance which changes as said rotor is rotated so that as said rotor is rotated different voltages are induced in said coils by the flux of said trigger magnet at different angular positions of said rotor, said two coils being located relative to said leakage fiux field and the field of said triggering magnet flux that in one of said coils the flux of said leakage flux field and the flux of said triggering magnet travel in the same direction relative to the axis of said one coil and in the other of said coils the flux of said leakage flux field and the flux of said triggering magnet travel in the opposite directions relative to the axis of said other coil, means connecting said two coils in series with one another so that the voltages induced therein by said leakage flux are in series bucking relation to one another and the voltages induced therein by said triggering magnet flux are in series aiding relation to one another, and means connecting said coils to said electronic switching device for supplying triggering signals thereto for switching it between said first and second states.

2. The combination defined in claim I further characterized by said two coils being arranged with their axes located generally in a plane passing through the axis of said rotor.

3. The combination defined in claim I further characterized by said triggering magnet and said two triggering coils being part ofa triggering magnet and coils assembly fixed relative to the stationary structure of the associated engine.

4. The combination defined in claim 3 further characterized by said triggering magnet and coil assembly including a core of magnetic material including two spaced legs, said legs of said core being located generally in a plane passing through the axis of said rotor, and said two coils each being received on a respective one .of said two core legs.

5. The combination defined in claim 1 further characterized by said flux circuit providing means for said trigger magnet including at least one elongated magnetic irregularity located generally in a plane passing through the axis of said rotor and rotated in unison with said rotor, and said triggering magnet said two triggering coils being part ofa triggering magnet and coil assembly located adjacent the rotary path of said irregularity, said triggering magnet and legs located generally in a plane passing through the axis of said rotor and extending toward said rotary path of said elongated irregularity so that as said irregularity passes said legs it momentarily varies the reluctance of the flux path between the ends of said two legs,

said two triggering coils each being received on a respective one of said two legs.

6. The combination defined in claim further characterized by said elongated magnetic irregularity comprising a radially outwardly projecting and axially extending strip of magnetic material in said rim of said rotor.

7. The combination defined in claim 5 further characterized by said rotor including an axially elongated hub, and said elongated magnetic irregularity comprising a radially outwardly projecting and axially extending strip of magnetic material on said hub of said rotor 8. The combination defined in claim 5 further characterized by said at least one permanent magnet being one of a plurality of magnets carried by said rotor rim and assembled in a circumi'erential series, said magnets being circumferentially spaced from one another and being tangentially magnetized 9. The combination defined in claim 1 further characterized by said rotor having a rim of nonmagnetic material and said at least one permanent magnet being carried by and fixed to said rim, said flux circuit providing means for said trigger magnet including at least one axially extending strip of magnetic material located at one point along the circumference of said rim, and said triggering magnet and said two triggering coils being part of a triggering magnet and coil assembly located adjacent said rotor rim, said triggering magnet and coil assembly including a core of magnetic material having two legs extending generally radially inwardly toward said rotor rim adjacent the path of said strip of magnetic material and spaced from one another axially of said rotor so that as said strip of magnetic material passes therebeneath it momentarily varies the reluctance of the flux path between the ends of said two legs, said two triggering coils each being received on a respective one of said two legs.

10 The combination defined in claim 1 further characterized by said rotor including a rim carrying said at least one permanent magnet and an axially elongated hub, said flux circuit providing means for said trigger magnet including at least one axially extending strip of magnetic material located at one point along the circumference of said hub, said triggering magnet and said two triggering coils being part of a triggering magnet and coil assembly located adjacent said axially elongated hub and including a core of magnetic material having two radially inwardly extending legs spaced axially of one another adjacent the path of said strip of magnetic material so that as said strip of magnetic material passes therebeneath it varies the reluctance of the flux circuit between said two core legs, said two triggering coils each being received on a respective one ofsaid two core legs.

22 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3 .623 .467 DatedNov'ember 3O 1971 Inventor(s) Michael J. Piteo It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[- ABSTRACT, line 2 "a a" should be --of a--.

Col. 2, line 58, "suitable" should be --suitably--. Col. 3, line 38, "29" should be -39--. C01. 4, line 43, "valve" should be -va.lue. Col. 4, line 62, "passes" should be --pa.ssage--. Col. 5, line 3, "degree" should be --degrees--. Col. 5, line 44, "magnetic" should be --magnet. Col. 6, line 68, after "magnet" insert --and--. Col. 6, line 71, after "said triggering magnet and" insert --coil assembly including a core of magnetic material having two-.

Signed and sealed this 13th day of June 1972.

(SEAL) Attest:

EDWARD M. FL ET CHER JR ROBERT GOT TS CHALK Attesting Officer Commissioner of Patents 

1. In a breakerless ignition system for a spark-ignited engine the combination comprising: a permanent magnet alternator having a rotor rotated in synchronism with the operation of said engine, said rotor Including at least one permanent magnet establishing a leakage flux field in the vicinity of said rotor, a spark gap ignition device, means including an electronic switching device for causing the occurrence of a spark at the spark gap device as said switching device is switched from a first state to a second state, a triggering magnet, two triggering coils located near said rotor so as to be within said leakage field, means providing a circuit for the flux of said triggering magnet which circuit passes through both of said triggering coils and has a reluctance which changes as said rotor is rotated so that as said rotor is rotated different voltages are induced in said coils by the flux of said trigger magnet at different angular positions of said rotor, said two coils being located relative to said leakage flux field and the field of said triggering magnet flux that in one of said coils the flux of said leakage flux field and the flux of said triggering magnet travel in the same direction relative to the axis of said one coil and in the other of said coils the flux of said leakage flux field and the flux of said triggering magnet travel in the opposite directions relative to the axis of said other coil, means connecting said two coils in series with one another so that the voltages induced therein by said leakage flux are in series bucking relation to one another and the voltages induced therein by said triggering magnet flux are in series aiding relation to one another, and means connecting said coils to said electronic switching device for supplying triggering signals thereto for switching it between said first and second states.
 2. The combination defined in claim 1 further characterized by said two coils being arranged with their axes located generally in a plane passing through the axis of said rotor.
 3. The combination defined in claim 1 further characterized by said triggering magnet and said two triggering coils being part of a triggering magnet and coils assembly fixed relative to the stationary structure of the associated engine.
 4. The combination defined in claim 3 further characterized by said triggering magnet and coil assembly including a core of magnetic material including two spaced legs, said legs of said core being located generally in a plane passing through the axis of said rotor, and said two coils each being received on a respective one of said two core legs.
 5. The combination defined in claim 1 further characterized by said flux circuit providing means for said trigger magnet including at least one elongated magnetic irregularity located generally in a plane passing through the axis of said rotor and rotated in unison with said rotor, and said triggering magnet and said two triggering coils being part of a triggering magnet and coil assembly located adjacent the rotary path of said irregularity, said triggering magnet and coil assembly including a core of magnetic material having two legs located generally in a plane passing through the axis of said rotor and extending toward said rotary path of said elongated irregularity so that as said irregularity passes said legs it momentarily varies the reluctance of the flux path between the ends of said two legs, said two triggering coils each being received on a respective one of said two legs.
 6. The combination defined in claim 5 further characterized by said elongated magnetic irregularity comprising a radially outwardly projecting and axially extending strip of magnetic material in said rim of said rotor.
 7. The combination defined in claim 5 further characterized by said rotor including an axially elongated hub, and said elongated magnetic irregularity comprising a radially outwardly projecting and axially extending strip of magnetic material on said hub of said rotor.
 8. The combination defined in claim 5 further characterized by said at least one permanent magnet being one of a plurality of magnets carried by said rotor rim and assembled in a circumferential series, said magnetS being circumferentially spaced from one another and being tangentially magnetized
 9. The combination defined in claim 1 further characterized by said rotor having a rim of nonmagnetic material and said at least one permanent magnet being carried by and fixed to said rim, said flux circuit providing means for said trigger magnet including at least one axially extending strip of magnetic material located at one point along the circumference of said rim, and said triggering magnet and said two triggering coils being part of a triggering magnet and coil assembly located adjacent said rotor rim, said triggering magnet and coil assembly including a core of magnetic material having two legs extending generally radially inwardly toward said rotor rim adjacent the path of said strip of magnetic material and spaced from one another axially of said rotor so that as said strip of magnetic material passes therebeneath it momentarily varies the reluctance of the flux path between the ends of said two legs, said two triggering coils each being received on a respective one of said two legs.
 10. The combination defined in claim 1 further characterized by said rotor including a rim carrying said at least one permanent magnet and an axially elongated hub, said flux circuit providing means for said trigger magnet including at least one axially extending strip of magnetic material located at one point along the circumference of said hub, said triggering magnet and said two triggering coils being part of a triggering magnet and coil assembly located adjacent said axially elongated hub and including a core of magnetic material having two radially inwardly extending legs spaced axially of one another adjacent the path of said strip of magnetic material so that as said strip of magnetic material passes therebeneath it varies the reluctance of the flux circuit between said two core legs, said two triggering coils each being received on a respective one of said two core legs. 